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Saturday, June 23, 2018

Particle Physics now Belly Up

Professor Ben Allanach is a particle physicist at Cambridge University. He just wrote an advertisement for my book that appeared on Aeon some days ago under the title “Going Nowhere Fast”.

I’m kidding of course, Allanach’s essay has no relation to my book. At least not that I know of. But it’s not a coincidence he writes about the very problems that I also discuss in my book. After all, the whole reason I wrote the book was that this situation was foreseeable: The Large Hadron Collider hasn’t found evidence for any new particles besides the Higgs-boson (at least not so far), so now particle physicists are at a loss for how to proceed. Even if they find something in the data that’s yet to come, it is clear already that their predictions were wrong.

Theory-development in particle physics for the last 40 years has worked mostly by what is known as “top-down” approaches. In these approaches you invent a new theory based on principles you cherish and then derive what you expect to see at particle colliders. This approach has worked badly, to say the least. The main problem, as I lay out in my book, is that the principles which physicists used to construct their theories are merely aesthetic requirements. Top-down approaches, for example, postulate that the fundamental forces are unified or that the universe has additional symmetries or that the parameters in the theory are “natural.” But none of these assumptions are necessary, they’re just pretty guesses.

The opposite to a top-down approach, as Allanach lays out, is a “bottom-up” approach. For that you begin with the theories you have confirmed already and add possible modifications. You do this so that the modifications only become relevant in situations that you have not yet tested. Then you look at the data to find out which modifications are promising because they improve the fit to the data. It’s an exceedingly unpopular approach because the data have just told us over and over and over again that the current theories are working fine and require no modification. Also, bottom-up approaches aren’t pretty which doesn’t help their popularity.

Allanach, as several other people who I know, has stopped working on supersymmetry, an idea that has for a long time been the most popular top-down approach. In principle it’s a good development that researchers in the field draw consequences from the data. But if they don’t try to understand just what went wrong – why so many theoretical physicists believed in ideas that do not describe reality – they risk repeating the same mistake. It’s of no use if they just exchange one criterion of beauty with another.

Bottom-up approaches are safely on the scientific side. But they also increase the risk that we get stuck with the development of new theories because without top-down approaches we do not know where to look for new data. That’s why I argue in my book that some mathematical principles for theory-development are okay to use, namely those which prevent internal contradictions. I know this sounds lame and rather obvious, but in fact it is an extremely strong requirement that, I believe, hasn’t been pushed as far as we could push it.

This top-down versus bottom-up discussion isn’t new. It has come up each time the supposed predictions for new particles turned out to be wrong. And each time the theorists in the field, rather than recognizing the error in their ways, merely adjusted their models to evade experimental bounds and continued as before. Will you let them get away with this once again?

60 comments:

You don't have to worry they will repeat the same mistakes - the next generations will do that for them.

Please what do you think of chances that some important clue (beyond SM) is maybe hiding in the LHC data but it is not easy to see (because of the noisy backgrounds, preprogrammed triggers in the data filters, etc.)?

Will I let them get away with this once again? Alas dear Dr. H. No one listens to me... but I am working on an essay related to your book. My goal is to argue that while beauty does not guarantee truth it will turn out that the true theory must be beautiful... Will share when ready..

Professor Ben Allanach "Behind the question of mass, an even bigger and uglier problem was lurking in the background of the Standard Model: why is the Higgs boson so light? In experiments it weighed in at 125 times the mass of a proton. But calculations using the theory implied that it should be much bigger – roughly ten million billion times bigger, in fact This super-massive Higgs boson is meant to be the result of quantum fluctuations: an ultra-heavy particle-antiparticle pair, produced for a fleeting instant and then subsequently annihilated. Quantum fluctuations of ultra-heavy particle pairs should have a profound effect on the Higgs boson, whose mass is very sensitive to them. The other particles in the Standard Model are shielded from such quantum effects by certain mathematical symmetries – that is, things don’t change under transformation, like a square turned through 90 degrees – but the Higgs boson is the odd one out, and feels the influence very keenly.

Except that it doesn’t, because the mass of the Higgs appears to be so small. One logical option is that nature has chosen the initial value of the Higgs boson mass to precisely offset these quantum fluctuations, to an accuracy of one in 1016. However, that possibility seems remote at best, because the initial value and the quantum fluctuation have nothing to do with each other. It would be akin to dropping a sharp pencil onto a table and having it land exactly upright, balanced on its point. In physics terms, the configuration of the pencil is unnatural or fine-tuned. Just as the movement of air or tiny vibrations should make the pencil fall over, the mass of the Higgs shouldn’t be so perfectly calibrated that it has the ability to cancel out quantum fluctuations........"

Sabine, what do you think keeps the Higgs boson so light? is it fine tuning, new unknown physics, or something wrong with QFT? or maybe there are no heavier particles than the top quark?

Particle Physics is certainly stuck, but it has nothing to do with the way theorists have been working. The problem is simply that there is no new physics within the energy and luminosity reach of the LHC or any other experiment.

It does not matter whether SUSY is right, or string theory or multiverses, or whether they tried bottom up or top down, or whether they look for mathematical beauty or something else. If there is no physics beyond the standard model to be found by the current experiments then it makes no difference what approach to theory they take.

Some of the triggers and searches may have been optimised to help find SUSY, but by now the experiments have covered a very wide range of possible physics. The experimenters are not such dummies that they only allow for the favoured theories. If there was anything to find in the collected data analysed so far it would have been seen. The limited imagination of theorists never stopped them before.

Hi Sabine. I agree that supersymmetry has some aesthetic appeal, because it is a rather direct and simple consequence of quantum mechanics and relativity. But surely the minimal supersymmetric standard model should not be described as pretty. It is based on an unknowable invisible sector where supersymmetry is broken, and it has hundreds of soft breaking parameters. These are motivated by the fact that any simple model with susy is clearly wrong. And that is what Ben Allanach and many others have been using for many years. To describe it as `top down' seems wrong to me. Surely it is as ugly and unmotivated as a mud fence? What do you think?

In my opinion, there is a place for top-down approaches, but it is limited because in my view top-down approaches are inextricably intertwined with paradigm changes, and paradigm changes are rare.

If the Mayans had conceived of planetary motion to explain the astronomical patterns they saw, then that would have been a paradigm change. Of course, Newton's physics and Einstein's relativity were paradigm changes, as was the "modern" quantum mechanics.

What they all have in common is that they integrated a lot of seemingly disparate data into a unified conceptual whole using a small set of key ideas as its foundation *which were already supported by the data*.

Arguably, the lack of success of supersymmetry could have been foreseen from the beginning because the key idea at its foundation, the existence of superpartners, was never supported by the data.

I think it is in these kinds of situations that aesthetic criteria as criticized in your book tend to be the most pernicious and harmful because they give a false sense of support for a hope that just isn't based on any objective evidence.

I point this out because in other contexts aesthetic criteria might be useful (namely when they are in sync with the data), and not being clear on this can lead to the danger of critics and proponents of aesthetic criteria talking past each other.

To see the contrast, imagine how discussions would go if there had been evidence, among the entire particle zoo, of even just one particle that could be conceptually framed as a superpartner in supersymmetry when it was first proposed.

A call to arms. But you might need to offer your activists more specific guidance. If the practice of particle physics now consists of nothing but predictions of new particles that never appear, a naive reader might suppose the objective to be, close down the LHC and defund research that predicts new particles. If that is not the objective, what is? Defund research that employs the principle of naturalness? Defund research that fails to find the predicted new particles after a specific number of publications making the predictions? Fund only research that meets certain criteria? But if so, what criteria?

You are mixing supersymmetry and the Minimally Super Symmetric Standard-model (MSSM).

Supersymmetry is a mathematical concept, and as such it cannot be ruled out by experiment.

MSSM takes the standard model of particle physics and modifies it, by making it supersymmetric. This fits exactly with your definition of the "bottom-up" approach. MSSM is also, at least in my opinion, a very ugly theory. I really think that by blaming MSSM researchers that their theory is beautiful you are doing them a disservice.

I agree with your sentiments; moreover, there is more. Mathematics is necessary but not sufficient. Comparative Science and Relational Complexity needs to be added into the mix. Verlinde points out that “information” is not well understood by conventional physics, and I would argue that applies to mathematicians (and even computer scientists) in that they are too stove-piped to see the “relational information” and MEANING-FUL information connections to the physical world processes. The simple Shannon information or quadratic bound probability statistics just doesn’t cut the Dedekind unkind cut. The siren call of Tarski’s monster and smooth seduction of things like Jones’ polynomials assume unreasonable continuity and infinite symmetries (ala QM, ST, MT, or QG). The overarching framework of the sporadic groups (finite, fixed point, and discrete) with the background foundations of computation and multiple mathematical areas (like Moufang loops and Division algebras), one can make a preordered correspondence (not a correlation) to the Standard Model concepts and percepts, and go beyond, to undermine some of glosses as “particle”-“anti-particle” or “matter”-“anti-matter” incomplete simplifications.

Not even wrong — but incomplete, in the Lost and Found of Mathematics. Still reading your book. Bravo.

I don't know. What I am saying is that the reasons many particle physicists have quoted for why there should be something to find are not good reasons. This doesn't mean there is nothing to find. I'm not a prophet. The only way to find out is to look. Best,

Once you want the SM to be natural and you want this to happen with SUSY, you arrive at the necessity to find susy-particles at the LHC. Of course you can't rule out supersymmetry per se, you only rule out specific models. I am not talking about the MSSM - this has been ruled out long ago. Of course people use other simplified models now. And will continue to use them if they can. Best,

Unfortunately I don't have access to the article that you cite. However, I started reading a book by Adam Becker, titled " What is Real" Subtitled 'The Unfinished Quest for the Meaning of Quantum Physics'. His more historical and less technically focused discussion seems to be heading in some what the same direction.That is: A herd mentality seems to be driving the direction of quantum foundations research. Obviously personality and historical precedence may have unfortunate consequences for the development of innovative thinking.

I have a list in my book. But to make it brief, there isn't remotely enough pushback on nonsense claims, neither from inside the community nor from the public.

I have some fairly recent examples here. There we have rather prominent particle physicists in rather prominent outlets making false claims and no one raises an eyebrow, nothing is ever corrected. Another example that comes to my mind is Hertog, who still boldly goes around and claims that his model can be tested with observation (it can't - the paper doesn't even contain a prediction).

Now look, these are but a few recent cases but I think they serve to highlight the problem. There are a lot of articles in the pop sci media that spread falsehoods.

For one I think journalists should be more critical. Like, maybe if a physicist claims to make an observational prediction, ask what the prediction is. Ask if the supposed prediction doesn't come true if it rules out the model. For particle colliders in particular, when they speak of naturalness, ask them why believe in naturalness. As them why they believe in supersymmetry. Ask them whether their career depends on their papers being well-cited. Ask them whether they feel pressured to produce papers.

As members of the general public I hope people will become more vocal in their complaints about uncritical science journalism, and also that they will themselves ask the scientists some hard questions about why they believe what they believe in. Best,

I have little interest in ideas about top-down vs bottom-up arguments. The simple message that appears to be growing in volume is that nature is simply different than what we have imagined. Some of the structures developed may play a role in nature, maybe others are wrong.

Renormalization group flow might be at fault. This assumes perturbative QFT, and for all we know this might only be a low energy approximation that can't be extended beyond the standard model energy at say 10 or so TEV. RG flow is similar in funny ways to fluid flow, and for that matter why do we assume it is a laminar flow from the string-Planck energy? It could have bifurcation physics, forms of chaos physics, it could have analogues to turbulent flow. Maybe it is completely wrong and there is something entirely different, solitons or nonlinear physics or … ?

Quantum gravity may be a similar kettle of fish that we have wrong in certain ways. Spacetime appears to be a classical construction. The underlying quantum mechanical basis has a number of possibilities. There are some existing structures that may or may not apply. These are supersymetry, entanglement condensates, the so called entanglement entropy force of gravity, BCFW realizations as an on shell description, related amplituhedron theory of Arkani-Hamed et al, or maybe something else. There may be entirely different concepts we need to apply.

The current crisis in particle physics is in many ways a good thing. Current phenomenology appears to be collapsing and this really clears the playing field. Established people who have built hard careers for the last several decades are now facing the eclipse of their work and the end of their careers. This means other people who have been sidelined for years or younger people can jump into the game and start afresh. The most important ingredient one needs is imagination.

I just don’t get it: what are the g-2 anomalies? What are the MiniBooNE results? Is the neutrino its own anti-particle? How many dark matter particle types have been ruled out by experiments? What are EeV cosmic rays?

Maybe if just 1% of the LHC funding were to be spent on innovative experiments, a lot more new physics would be found.

I'm your target market: the semi-educated layman who just can't get enough of this stuff. And I just read your book. I went into it expecting a contrarian rant fueled by professional grudges - but instead found it very interesting, edifying and funny. I'll be pushing it on friends.

The discussion of cognitive biases is spot on - and so are the observations that intelligence is no protection, and solutions aren't obvious.

For a long time there was a debate as to whether light was a wave or a particle. There was evidence for each, and at various times experiments and theory favored one and then the other. The resolution was stranger than anyone expected, but a major clue was from light emitted by very small particles.

I get the impression that in 50, or perhaps 100 years, historians of science and science popularizers who present the narrative will point out that we had an awful lot of clues, but, as with our theories of light, we spent a lot of time looking at the wrong things. The LHC is not giving us useful clues, and we have no reason to believe that building a more powerful accelerator will give us any useful clues.

There are so many places where relativity and quantum theory are in conflict. There are an awful lot of clues.

All they need is more money and a new computer, then they'll find new physics. It's really scary when an entire scientific field could tilt science to their direction with billions of dollars of funding riding on the line.

The Higgs mass isn't any more in need of explanation than the masses of the other particles in the standard model. I explain this in my book but I have a somewhat more detailed summary here.

Now you can ask of course why do the masses of the particles have the values that they have. I don't know. We do know, however, that some combinations are ruled out because they wouldn't be compatible with stars/galaxy formation or other preconditions for life. We also know that if you require asymptotic safety, then the mass of the Higgs must be near by the mass of the top quark, which for what I am concerned nicely explains why it's so light (see this paper). Note that in this case the Higgs mass is still "unnatural". Best,

Funny you'd say that, indeed I have the same suspicion. I have said this elsewhere, but let me just repeat that I suspect technical naturalness does have a rigorous mathematical basis, it's just that we're missing some assumptions here. Perturbative renormalizability of the next-level theory may be one of them. See also my previous comment about asymptotic safety tying the Higgs mass to the top-quark mass (or the mass of the heaviest fermion, respectively). Best,

I enjoyed reading your book. But I have a dissenting view on supersymmetry. I think susy is exact and beautiful. The trick is susy should be considered reborn for preons. There is no superpartner problem. For the first step, see https://doi.org/10.1016/j.nuclphysb.2018.04.021 or arXiv:1805.03013

The question comes down to where the new developments will come from. And that is unanswerable.

If we look at the major breakthroughs in physics, they all gave us a whole new perspective on reality, one that was unthinkable before. Newton showing that the planets move like an apple, introducing a whole new area of mathematics in the process. General Relativity and Quantum Mechanics both made the unthinkable predictable reality. And both were unthinkable to many even years after they had been proven right. There are still people advertising on this blog that claim QM and GR are not true.

If there is anything we can expect from a genuine new breakthrough, it will be that it was literally unthinkable before we derived it. But it is still fun to speculate.

“The problem is simply that there is no new physics within the energy and luminosity reach of the LHC or any other experiment.”

Alternatively, consider the possibility that deep processes of our universe are observable within our work-a-day reality if we simply have right angle of apprehension.

For example, the steady stream of water from a garden sprinkler impacts the leaf of a large sunflower plant. The leaf is pushed away and then swings back to be pushed again and a cyclical dynamic ensues. Within certain parameters this cycle appears metronomic, but increasingly fine-grained measurement will reveal multiple digit time distinctions, one cycle to the next. We find a robust dynamic motif with wide ranging variety of expression. Kindred dynamics are a readily observable property of our universe. So, here’s the question:

Why is it that iterative dynamics are pervasive in the universe over spatial and temporal dimensions varying by many orders of magnitude and further, that they arise from a multiplicity of distinct mechanisms?

This seems like a legitimate question.

Can its answer be found within the Standard Model, our most explicit description of fundamental processes? And if that is not the case, does it suggest that there may be a deeper principle at work, one in which particle physics emerges and one that would, if understood, offer a rationale for a variety of otherwise inexplicable observable phenomenon.

@Jean Tate. If neutrinos were their own antiparticles, newly formed or merged neutron stars could not cool their cores. The extraordinary neutrino flux already has problems diffusing through the matter density. Mutual annihilation to anything else would be trapped energy. Observation of GW170817 neutron star merger would diverge from models.

Neutrinoless double beta-decay is looking for nothing on a log scale. Job security!

In reply to "unknown" I do not think that "we're done." We are stuck without further experimental input, but there is a lot more to do. We may get some new data or we may not. You can't blame any theoretical approach for that. Theorists were right to explore ideas like supersymmetry. If they had not we would not understand the significance of the lack of new physics as well as we do.

If anything theorists need more freedom to plough their own furrow. Telling them how to do it or how not to do it is not going to help. I doubt we will see another bigger accelerator until there is good reason to think it will bear fruit. Other experiments such as neutrinos, proton decay, cosmology etc, are the best hopes for new input.

I know little, but whether top-down or bottom-up, the evolution of particle physics may have branched off towards a dead end. Perhaps the devices which experiment with the electro-magnetic containment of plasma fields will yield enlightenment and a new branch which leads further.

Fundamental physics is stuck, because we've encountered a "desert" and the "beautiful theories" aren't panning out experimentally. But particle physics is not.

There are plenty of worthy problems out there that should, in principle, be solvable without any beyond the Standard Model or beyond General Relativity physics, and which could justify further particle accelerator physics, especially in QCD which is the only part of particle physics where it isn't that uncommon to get results that differ materially from a priori predictions for experiments.

For example, we still don't really understand why we have the spectrum of scalar and axial vector mesons we do, or why we don't observe free glue balls (hadrons made entirely of gluons) even though free glue balls were described theoretically in QCD just a few years after QCD was invented in the early 1970s and the properties of free glue balls involve only a single fundamental constant since they don't have quarks. There are some pretty plausible post-dictions of particular mesons that we do see, but really no first principles explanation of the spectrum we see in the way we do for pseudo-scalar mesons and baryons. I also think it is quite possible the while all rules of QCD are true, that we are missing a rule or two that could explain these phenomena (e.g. all hadrons must have quarks) that could illuminate these and other phenomena.

Similarly, we are only in the infancy of explaining "hadron molecules" (e.g. systems of two distinct mesons bound to each other by something similar to the residual nuclear binding force between protons and neutrons in atomic nuclei).

Along the same lines, particle physics are discovering new hadrons that have been predicted and new hadrons that aren't yet characterized well enough to see if they were predicted every month or two, it seems. Discovering a new, previously predicted hadron experimentally may not be quite as awesome as discovering a new, previously predicted chemical element, but it isn't a case of complete scientific stagnation either.

We are also pretty much guaranteed to make progress in QCD simply by throwing more computing power at it, which with Moore's law, isn't that difficult to do in principle. We have lots of cases where we have experimental measurements in QCD that are accurate to parts per 100,000 or parts per million, but can only make theoretical predictions that are accurate to parts per hundred or parts per thousand, in part because the QCD coupling constant is only known to 7 parts per 1000 and the light quark masses are similarly not known very accurately (which in turn is the case because we can't calculate precisely enough to back physical constants out of experimental results very precisely). But, if we use the computing power necessary to do those to four or five loops instead of the current state of the art three loops, we could improve the accuracy of the QCD coupling constant value and the light quark mass values considerably. It is ugly physics, but it would have a lot of practical payoffs in all areas of QCD and in areas that don't obviously rely on QCD like muon g-2 calculations.

Similarly, we still have dozens of QCD predicted hadrons and hundreds of QCD predicted excited states of hadrons which we should be able to confirm the existence of simply with more brute force particle collisions at the LHC and similar experiments.

There are also problems like the muonic hydrogen problem that are unresolved and definitely involve particle physics, just not LHC scale colliders.

I have been a reader for a while and I keep coming to the same question. Are there experimental physicist working on particle physics in the scientific way (as opposed to the non-scientific that you so often describe) or the network of BSers occupy the whole area? In case there is people working in the scientific way (which I’m sure there is), how have they fared in the same time-frame (lets say the last 30 years)? In other words, can we compare the successful, demonstrated results obtained by both groups? How does it look, if we can check?

Well, it must be my personal conundrum and one whose answer is so well known that it needs no discussion here, but why is cyclical and wave-like dynamic such an integral phenomenon in the physics of the universe? Does it arise clearly from the Standard Model or is it merely taken as a given property to be mathematically described? Does it perhaps have its own alchemy of necessary ingredients?

There is mewing complaint here about the state of particle physics and no clear statement as to what is to be done about it. Perhaps in the present lull, someone would find time to answer my question.With my thanks,

So sorry for this situation -- but it was inevitable. You see, you physics folks are just pure mathematicians who unfortunately insist that your mathematics bear some relationship with measurable outcomes, what some call reality.

As a pure mathematician, I am not constrained by such silliness. If the math is beautiful, that is reason enough to pursue it. I say, go for beauty -- super symmetry, or whatever the most ambitiously gorgeous theory is, and then wait to discover a wormhole to the particular universe that fits your theory --

Oh, I guess I'm multi-versing, my apologies, I must return to computing the Graham's Number decimal digit of Tree(3).

My standard email is goldenfieldquaternions@gmail.com . I feel funny using another blog to establish another contact. Anyway, I there there are elements of chaos theory with bifurcations that are formally the same as Ginsburg-Landau based critical physics. I also worked up last decade this theory or model where perturbative QFT has a phase transition into physics more in line with knot theory. I got a lot of negativity on that.

@PhilG- If we're stuck without further experimental input, then is what we're doing science? Human beings are really good at constructing elaborate, self-consistent systems that have no relationship to observable reality (see: all of philosophy and theology (of every religion except yours, of course)). If theory can't be disciplined by experiment, it's not likely to be reliable.

Of course, there would be no circumstance where we would possibly need to rely on it, but that hardly seems like a recommendation.

P.S. I'm Jay. I don't know why Google gives my name as "unknown", but it's not just this blog and it's not just me.

Unknown Jay, the work theorists do is based on past experiments and confirmed or refuted by future experiments. Whether it is right or not is something that remains to be seen, but however they do it and whatever philosophical approach they take it is certainly science, not religion. I have not said that there will be no useful future experimental input, just that we are not finding it at present.

Personally I suspect where physics errs is in the assumption the math of GR and QM replicates how nature gets to those predictions. I’m not questioning their usefulness or accuracy at all, I’m merely speculating there is a possibility that things like the wave function and the curvature of spacetime don’t exists in nature in spite of their predictive power and accuracy, ergo they also create some of the difficulties physics has too.

thanks, i was of the understanding that fermions and wz bosons get their mass from the higgs field, though i don't entirely understand why a top quark interacts more strongly with the higgs than say an electron or up and down quark

and the higgs mass is due to its interaction with itself.

a more fundamental theory then would allow the theorist to calculate from first principles every fundamental fermion strength of interaction with higgs field via yukawa coupling

I'm not a physicist, and this comment is not directed at you personally, but it sounds like scientist/physicist these days need to learn how to play. They are so dogmatic and have so much tied to an idea that they can't even acknowledge ideas that are contrary to the mainstream without melting down.They are like kids trying to get the NextGen iPhone when they don't even use what they currently have to its full potential by any stretch of the imagination.

Play with the particles you know. Do weird things to them. Play in the quantum sandbox for the laughs and joy of it. Can't figure out something? Make a game of it and give it to the world to play with. Stop closing minds to things just because we can't explain them or they don't fit with whatever pet theory happens to be in ascendance at the moment. Even if you run down a rabbit hole on some theory and it turns out wrong, you will learn as much from your mistakes as you do from your successes.

Commercialized science has been a horrible idea, and peer review has ended up at its inevitable, corrupt, conclusion. I quit trusting science because it is even less internally consistent than religion. It no longer follows its own precepts and rules. It has become a religion. A matter of faith as opposed to evidence, from quantum physics to biology to Astrophysics. A poor shrine to man's vanity and arrogant pride at his own cleverness.

We (those that follow scientific research but are not scientist) don't know who to trust or what to believe, and must always ask "Who funded this..?"

I bought your book! I don't understand anything. But i will keep re-reading it until you do. Now that you are almost free to travel, will you be visiting NYC to promote your book? Please let your readers know!

Hello Dr. H. Here is my article inspired by your book. I emphasize that like much of modern physics it is a view that amounts to one possibility among many, but in your book you do in a back handed way acknowledge that this possibility remains open.

There are two links. The first to a copy of my Amazon review preceded by a short extra commentary on what in my review I called your "secondary concern", the politics and economics of the academic business. The second is the to essay you inspired. Both are cross linked into the other at their beginning so you can choose either and get to the other.

The review: https://ruminations.blog/2018/06/27/book-review-lost-in-math-by-s-hossenfelder/

and the essay: https://ruminations.blog/2018/06/27/why-true-physical-theories-are-beautiful/

The anti-de Sitter spacetime is where quantum gravitation really exists. It is then "what if? time." What if the AdS with its causal regions defined by null surfaces, in two dimensions that correspond to arcs, has a junction conditions across these null surfaces. These null surfaces define a holographic screen with a positive energy junction, and the observable universe is on such a holographic screen.

The situation is far from hopeless, and as I see it this is not at all unexpected. The bosonic string world sheet is essentially an AdS_2, and this has two tachyonic states that have negative energy. The vacuum energy is negative, which means an unstable vacuum. Out of this vacuum should come a fountain of quantum states. For AdS_5 the quantum states that emerge might then be given by the Petrov types and are then perturbed FLRW or de Sitter spacetimes. This endless production might then define these junction conditions. This would have connections of edge states and symmetry protected topological states.

This is all about "what if?" I don't see that situation as hopeless, even if we do not live in an AdS spacetime. We might at best be embedded in such on a null/holographic screen.

“If you gotta pretty good idea of what you’re looking for,Then you gotta pretty good idea of what you’ll find.You don’t have to go so very far these days,To find yourself a made up mind.”Peter Mulvey, Letters From A Flying Machine, “Kids in The Square”

Continuing a discussion obliquely relevant to the hiatus in theory-development in particle physics…

Taking Maxwell’s electromagnetic field equations as indicative of all other fields, then these fields are eloquently descriptive of wave-like, iterative dynamics as a given phenomenon, but are mute as to why they exist. They say a great deal about the biology of the tree but nothing about the ecology of the forest. Or perhaps better, they examine the part but fail to apprehend the whole.

Is it allowed to understand the actual origin of iterative dynamics and why they are pervasive in the universe over spatial and temporal dimensions varying by many orders of magnitude, and further, why they arise from a multiplicity of distinct mechanisms? Would this understanding create a little breeze to fill theoretical sails?

Definition: Nature is natural.Fact: some great apes are uneasy about some of the numbers in nature.Small "unnatural" number: one species out of 8.7+-1.3 million is doing physics.And worrying about small numbers...J.R. Cudell

One of the blog sites I like to read is 4gravitons (https://4gravitons.wordpress.com/), the latest posting was a summary of Strings 2018 at OIST which included this:

"Talks here focused on a few big questions: 'Can we classify all quantum field theories?' 'What are the general principles behind quantum gravity?' 'Can we make some of the murky aspects of string theory clearer?' 'How can string theory give rise to sensible physics in four dimensions?'" (emphasis added)

https://4gravitons.wordpress.com/2018/06/29/strings-2018/

That last topic (which I italicized) clearly implies that -- currently -- even its advocates think string theory does not give rise to sensible physics in four dimensions. That topic appears to fit the definition of a buried lede. Unless one can show how sensible physics can arise in four dimensions from string theory(s) I don't think the rest of the topics matter much.

I am 20% through Bee’s book. Will it influence research funding to be more practical. I doubt it can be easily influenced by books or blogs.

Here’s a plan: Throw out all the goofy theories and go back about 100 years and move forward deliberately, never accepting nutty stuff like uncertainty and other paradoxes. There is a natural physical solution that is a solution to all the equations but no one IN the field has found it. It is there. I am not in the field and I found it. It’s actually quite fascinating and sensible. A whole new era will start once it is accepted. And there is not that much to object to. It is kind of painfully obvious once you see it. It is right under the standard model. The physicists of 100 years ago were far closer than the physicists of today. 10,000 physicists will need to be repurposed, as well as the experiments, but that is all ok in a golden era. Lots of new physics is needed to learn how to control it and apply it.

Hi Sabine, You mentioned in your interview by John Horgan the Asymptotically Safe Gravity as what looks to me more of a bottom's up approach to the problem of quantum gravity that does not require supersymmetry. I have read up elements of the theory (Friederich 2017) and in the article it is mentioned that it attributes fractal like properties to space time. There has been some recent work disproving the Penrose cosmic censorship conjecture that seems to lead to the conclusion that a fractal space time exist beyond the Cauchy horizon in a black hole (Quanta magazine May 17 2018 Kevin Harnett). Has anyone looked at a possible link between the two and using the Cauchy horizon as a boundary for the theory.Georges Fournier

As much as your criticism is punctual relevant, it lacks the fundamental (meaningful) consequence. SUSY is a "good" example. The reference to the lack of corresponding "particle accelerator results" (super partner particles) in the course of (indirect) detection, however, implies the reality of a supersymmetric order of nature. The assumption that a theoretical construct, born out of the “misery” of the SM, which possesses no real relevance to the “reader” except mathematical symmetries, which is believed true-existent and measurable, corresponds to the spirit of the times but is already completely absurd for rational logical reasons.

SUSY followers and SUSY critics have obviously forgotten the "nature of thoughts”. As a reminder, this is not about the meaningless question of what (physical) truth is, because a “thought model” is just a model of thought. But it certainly concerns the honest question to what extent a present model, for example for matter formation, is minimalistic and at the same time provides clear solutions.

Outlook: There are “lagrangian-density-free” and “differentialgeometrically-liberated”, consistent, formally analytically-predictable, interdisciplinary understandable alternative models to SM, ΛCDM and related theory concepts, but these were not created by quantum field theorists and may be, for emotional-ideological reasons not even understood, since the concept of mass-decoupled spaces, as required by the standard models, must be abandoned.